1. Field of the Invention
The invention relates to a device for training motorbike riders and in particular to a device for varying the angle of lean of a motorbike, in a safe and controllable manner, as it turns through a corner. The present invention consists of two structural frames or outriggers, attached to either side of the bike extending out for a few feet with a wheel at the end of the outriggers which is in contact with the ground until the lean angle of the bike exceeds 40 degrees. The position and angle between these outriggers and the bike can be incrementally controlled by the rider by means of a lever mounted on the handlebars and controlling the pressure inside two shock struts attached to both outriggers and to the bike.
The addition and employment of the invention allows a novice rider to overcome the natural fear that exists when the rider has to lean the bike over while turning a corner or when the rider suddenly leans the bike over to change direction quickly as is necessary to avoid an object in front of the bike.
This natural fear that occurs when a novice is learning to ride a motorbike when turning into a corner is very real and must be overcome for the rider to become skilled at handling a bike under a wide variety of road conditions.
To traverse a right hand corner for example, the bike handlebars must first be turned to the left, away from the corner. This causes the bike to fall or lean to the right, due to centrifugal force generated on the bike and acting in a direction away from the center of rotation so as the bike leans to the right, the front wheel automatically turns around to the right and helps to set the cornering radius of the bike and the bike's lean angle, as it goes around the right hand corner.
Since the bike has two wheels, it must be leaned into the corner deliberately by the rider, to offset the centrifugal force which is trying to overturn the bike to the left. The tighter the radius of turn and the higher the road speed, the more that the bike must be leaned over, in some cases as much as 40 or 50 degrees from vertical. For most novice riders, there is a natural fear of leaning the bike too far thus bringing the bike and their body dangerously close to the ground.
There is also a fear of causing the bike to fall down or in the act of leaning far enough to make a turn, impacting some structural parts of the bike against the ground such as the foot-rest or oil-pan. If this impact occurs, then weight is transferred off the wheels and the tires can loose traction, causing the bike to fall over to the right, which may trap the rider's leg against the ground.
There is also the danger of a bike being leaned into a corner too much, causing the rear or front tire to slip and turn the bike further into the corner. The rear or front tire may then regrip the road surface, creating a very strong force which tries to straighten the bike up and which can `high-side` the rider.
The definition of `high-side` as used in the disclosure is the action of a two-wheeled bike going through a corner and the front or rear wheel (or both) slips away from the cornering center then suddenly regrips the road surface, generating a large reaction force which acts to rotate the bike towards its vertical axis and which can be sufficiently strong to throw the rider off the bike.
The definition of `low-side` as used in the disclosure is the action of a two-wheeled bike going through a corner and the front or rear wheel (or both) slips away from the cornering center causing the bike to fall down.
The definition of lean angle is the angle from a line perpendicular to the ground of the bike's vertical axis as the bike leans over during a turn.
Another natural fear that exists for the rider, when trying to avoid an obstacle in front of the bike and quickly turning the bike to either side, and so causing it to fall over. These fears are of course enhanced in any reduced traction conditions.
Because of the nature of the dynamic forces acting on a motorbike as it goes through a corner at speed, and the inability of the bike's structure, to counteract these forces, it is necessary for the rider to learn to balance these forces by leaning the bike and his body towards or into the corner. If not done correctly, there is a considerable risk of the bike's tires loosing traction on the road or track surfaces allowing the bike to go into a skid and `high-siding` or `low-siding` the rider.
Leaning one's body with a bike into a corner runs counter to all basic instincts for the rider's safety as the preference is to maintain the body in a position close to vertical. To efficiently ride and maneuver a bike the rider must learn to lean his body with the bike and overcome this strong survival instinct.
The present invention is designed to teach the rider how to overcome this instinct and lean through a corner correctly at different speeds and corner radii and so allows him to gain confidence in his riding skills while eliminating many of the dangers described herein. The invention also allows the rider to overcome the fear of leaning his body over with the bike in a corner instead of trying to maintain his body in an upright position, which requires leaning the bike further over than is necessary. This has the advantage of less bike lean angle in a turn hence better use of the correct tire surface which creates a better traction situation. It also requires less work from the rider as he does not have to force the wheel over to get the correct lean angle, instead he uses his body to work with the bike to get the best lean angle. Another advantage of this correct lean angle is that in an accident situation, the rider can respond faster to the situation and turn the bike more quickly and so avoid a collision.
It is very important for the rider to learn to set the correct lean angle and hence turn radius at the start of the turn through a corner as quickly as possible so corrections are kept to a minimum. Each correction made through a turn creates a degree of instability of the bike and rider with a resultant reduction in traction. By overcoming the rider's fear of leaning the bike quickly and through steep lean angles, this allows the rider to quickly set the correct lean angle and so go through the corner in the best and safest possible manner.
2. Description of Related Art
There are a number of existing designs in the art where extra structures and wheels are added to a basic 2-wheeled bike. For instance, side-cars have been in use for some time and are added to transport another passenger or to carry payloads. Side-cars are fixed rigidly to the bike frame and although they add lateral stability to the bike, this is a secondary factor. Further, a side-car is only added to one side of the bike unlike the present invention which adds a structure to both sides of the bike.
In the case of a motorbike and side-car, the sidecar supplies a lot of the stability that is missing in a two wheeled vehicle and creates a much more stable platform for the rider. However the side-car is fixed to the side of the bicycle and does not move or rotate relative to the bike as the bike goes through a corner. The vertical center of gravity of the bike/side-car combination lies between the 3 wheels and so creates a moment (weight times distance) that counteracts the induced centrifugal force and subsequent moment created in the horizontal direction as the bike/side-car goes through a corner at speed. Also, unlike the present invention, the sidecar does not assist in the training of a bike rider who is learning to ride a bike with two wheels round a corner. As he is going through turns and corners on a bike, he must learn how much to lean the bike as he goes through the corner.
Further, a bike with side-car is designed to be a freestanding system, while the present invention applied to a 2 wheeled bike will allow the bike to lean over to either side. In the case of a bike plus side-car the bike cannot be leaned through corners, as the 3 wheels contacting the road act as a stable platform and lateral centrifugal forces are usually not sufficient to raise the side-car wheel off the ground, which would allow the bike to lean. This is especially true if a passenger is sitting in the sidecar or a payload is being carried.
Training wheels are also known in the art and can be used on a bike but they are generally rigidly fixed to the bike frame and while the bike is driven, They are used to limit lean angle of the bike to the angle set before they contact the ground. They do not include any of the control or incremental training features of the present invention.
Also known in the art is the BMW (Bavarian Motor Works) design of outriggers which are attached to the bike frame similar to the present invention, but they are positioned in a fixed relation to the bike frame with wheels attached to the ends of each outrigger, which have a space between both of the wheels and the ground while the bike is moving in a straight line. When the bike is leaned over sufficiently in a corner, one of the outrigger wheels touches the ground and so limits the amount of lean.
A shock absorber is also used in the design but only to reduce the impact forces in the case of a sudden lean that allows the outrigger wheel to hit hard on the road or track surface. This device is designed mainly to measure wet weather traction forces on different types of tires. It has no capacity to allow incremental lean angle changes to the system and can not be used for quick turn and steep lean angle tests as can be done by the present invention.
The BMW bike outriggers could high-side the rider in a corner, as they did not have close contact maintained between the outrigger wheels and the road as in the present invention.
There is nothing in the prior art that allows the rider to overcome his fears in the manner of the present invention. The performance of the present invention can also be easily adjusted by changing orifice sizes in the hydraulic cylinders which control the force required to change the lean angle for the rider. Thus control features of the invention can be changed to match the rider's confidence level as he improves his skills.